“I know people are worried about it," says Davidson, "but I think there will be a way around that rule.”

“I know that Steven has put in the groundwork already in an episode so that there can be more,” he assures fans in an interview with The Telegraph.

Doctor Who will celebrate its 50th anniversary with a special feature-length episode, The Day of the Doctor, on 23 November. The film will be screened simultaneously in 75 countries when it goes out on the BBC later this year.